Kontinuierliche faseroptische Dehnungsmessung im Stahlbetonbau

Thoma

Crepaz

2019

Self Cite

The method of fiber optic strain measurement offers promising perspectives for experimental research and also provides extensive new capabilities for the systematic monitoring of engineering structures. A robust but sufficiently sensitive configuration of measuring device and passive optical fiber is desirable in practical application. In this context, a total of five different optical measuring fibers were analyzed at the Chair of Concrete Structures at the Technical University of Munich (TUM) for different application variants using two measuring instruments on a prestressed concrete beam. Fiber optics, supplemented by conventional measuring technology, was able to detect elastic strain, crack formation, and decisive shear cracks of the fracture state.

Section: Principle Of Fiber Optic Strain Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distributed fiber optic sensing for crack detection in concrete structures

Thoma

Crepaz

2019

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“…To investigate the load‐bearing behavior of the stirrups, they were equipped with fiber‐optical sensors (see also References ) which guarantee a quasi‐continuous strain measurement along the bars. The position of the stirrups with intact fiber‐optical sensors in the test specimen and the stationing of the sensor along the stirrup are shown in Figure .…”

Section: Experimental Investigations On the Shear Behavior Of Prestrementioning

confidence: 99%

Precast bridge construction with UHPFRC—Shear tests and railway bridge pilot application

Schramm

2019

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Due to the favorable material properties, Ultra‐High Performance Fiber‐Reinforced Concrete (UHPFRC) opens up new potential for precast options in PC bridge construction. On that matter, this article outlines the application, the load‐bearing behavior and advantages of two different possibilities: slender prestressed bridge girders and a prestressed trough‐shaped bridge element. Prestressed bridge girders made of UHPFRC allow for the realization of very slender cross‐sections with thin webs. For these beams, the shear capacity is the governing design issue. Hence, further investigations on the shear behavior with a variation of the fiber content, the prestressing level as well as the amount of shear reinforcement were undertaken. In this context, also size effects were examined using specimens with different construction heights up to 1.0 m. To enable testing of a high number of specimens with realistic cross‐sectional dimensions and at reasonable effort, an innovative experimental setup was developed and used for the investigations. Apart from these laboratory tests the present article deals with the pilot application of a railway bridge made of UHPFRC in Germany. The design and construction process as well as measurement results of the load and deformation behavior of the prestressed precast bridge element are presented and discussed.

“…Furthermore, an innovative fiber optical measurement system was applied on a large scale to measure the strains on the concrete. This technique, which is based on the backscattering of a laser induced light signal (compare with Reference ), allows almost continuous and highly accurate measurements of the strains along a glass fiber cable with lengths of up to 50 m (sampling rates of about 1.0 mm). For this purpose, the fibers are attached to the surface with special adhesives; use within the tested members is also possible (installation of the fibers while the concreting).…”

Section: Testing Procedures and Measuring Techniquementioning

confidence: 99%

Full‐scale shear capacity testing of an existing prestressed concrete bridge

Gehrlein

2019

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Due to the relatively high average age of the existing bridges, a dramatic increase both in traffic volume and axle loads and because of modified design standards, a realistic prediction of the shear capacity of existing prestressed concrete bridges with little shear reinforcement has become an important topic in German research. In 2017, the Chair of Concrete and Masonry Structures of the Technical University of Munich (TUM), supported by the Federal Ministry of Transport and Digital Infrastructure, was given the unique opportunity to conduct full‐scale field tests at the Hammelburg Bridge built in 1955. According to systematic strength evaluations, many concrete bridges in Germany, especially those which were built prior to 1966, show severe (theoretical) deficits regarding longitudinal shear capacity. The results of the strength evaluation can often not be verified in the real bridges though. The primary objective of the field test therefore was to determine the actual shear capacity of existing prestressed bridges aiming at closing the gap between structural analyses and experience in regard to older concrete bridges. The article at hand presents the conceptual approach, the test set‐up and the execution of the in‐situ testing, the used measuring equipment and essential findings gained from the conducted full‐scale experiments. Furthermore, the results are discussed and the measured maximum loads of all five tests are compared to the results of different theoretical approaches and engineering models, respectively.